The X-51A before testing, handing from the wing of a B-52 bomber. AP Photo/U.S. Air Force/Chad Bellay.

The Air Force confirms that a hypersonic jet called the X-51A WaveRider crashed in the Pacific Ocean today after one of its control fins failed. The unmanned aircraft was launched from an Air Force B-52 bomber over Point Mugu Naval Air Warfare Center at around 11:36 this morning, Pacific time.

At first, the launch looked good. The WaveRider separated from the B-52 as planned, and its booster rockets fired properly. Then, after about 16 seconds of flight, the control fin was found to be faulty and the jet tumbled out of control.

"All our data showed we had created the right conditions for engine ignition and we were very hopeful to meet our test objectives," said Charles Brink, the project manager, in a statement. The failure, he said, was "unfortunate."

Researchers are analyzing data from the failed test, after which the Air Force says it will release the results of the investigation. The X-51A has had two previous successful tests, including one two years ago during which it flew for more than three minutes at five times the speed of sound.

With this latest test, the Air Force had hoped the speed would increase to 4,600 mph, roughly six times the speed of sound.

The Air Force hasn't disclosed the cost of the WaveRider program, but Globalsecurity.org, a website that tracks military spending, says the project has cost $250-300 million since it began in 2004. After today's test only one aircraft remains, and Air Force officials have not decided when or if it will fly.

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